Glossopharyngeal Neuralgia, An Usually Overlooked Diagnosis: A Prospective Single Center Observation Study

Abstract

Glossopharyngeal Neuralgia is often difficult to diagnose in view of its symptoms that overlap with many other regional causes. This subset of patients commonly visits otolaryngologists, dentists, oncologists only to be referred to the other and finally to the psychiatrist when the diagnosis is overlooked. We hereby present a prospective observation study of 26 cases of Glossopharyngeal neuralgia. In our observation we found a prevalence of 0.2% for glossopharyngeal neuralgia in our patients with facial pain, however amongst the neuropathic pain the GPN was more prevalent with about 35% of all the cases. Amongst the cases diagnosed with GPN we had 73.1% female predilection as compared to only 26.9% male. 53.8% of cases had left sided and 46.2% on the right sided making it non-significant in sidewise predilection.

Introduction

Weisenburg first described lancinating pain of the throat and the ear as a cause of Tic douloureux back in 1910 [1]. It was Harris who in 1921 coined the term “glossopharyngeal neuralgia” describing it as a painful syndrome characterized by paroxysms of unilateral and severe lancinating pain in the distribution of the nerve, which may be elicited by stimulation of trigger points in regions of the nerve [1]. Glossopharyngeal neuralgia (GN) can be described as a severe transient stabbing pain experienced in the ear, base of the tongue, tonsillar fossa, or beneath the angle of the jaw.

We hereby present a series of 26 cases presented to our outpatient department over a period of 18 months who had varied clinical presentation who were finally diagnosed to be glossopharyngeal neuralgia (GPN) and treated accordingly.

Study Objective

To study the prevalence of glossopharyngeal neuralgia amongst the patients reporting to out outpatient with history of pain in the head and neck region.

Materials and Methods

All the Patients reporting to the outpatient service of our department between January 2014 and July 2016, with pain in the head and neck region underwent a detailed history and examination and were given a pain diary to maintain to check on the frequency and intensity of the pain episodes. Patients were put through a thorough oro–dental, otolaryngologic and oncologic screening. All the patients underwent Orthopantomograph (OPG) and PA Skull radiographs to rule out dental cause of pain and styloid associated pain. After ruling out organic causes, pain or dysesthesia associated with the ear, faucial pillar, soft palate, base of tongue and throat were given a high suspicion towards glossopharyngeal neuralgia.

Diagnostic Glossopharyngeal nerve block was given using an intraoral anterior tonsillar pillar technique, via the premolar approach in all cases to confirm diagnosis [2]. In our patients we routinely used 2% Lignocaine for the diagnostic nerve block. The alleviation of pain to this block was considered to be confirmatory for the diagnosis of glossopharyngeal neuralgia.

Once the patients were diagnosed basic hemogram and baseline liver and renal function tests were done. Magnetic resonance angiography (MRI) with time of flight images focused on the glossopharyngeal nerve and its ganglia were advised to our patients to rule out any intracranial etiology for the condition. However not all cases could afford for MRI. All patients were initially put on Carbamazepine 100–200 mg 8 hourly, and an antianxiety drug Cap Duloxetine 30 mg twice a day. In cases of refractory GPN a second antiepileptic drug such as Tab Pregabalin 75–150 mg or Tab Gabapentin 300 mg along with an increase in the dosage of Carbamazepine to 300–400 mg eight hourly was advised. Supplementation of Methyl cobalamin and Thiamine were routinely done in all the patients.

Results

Seventy—four cases of eleven thousand and fifteen patients reporting with pain to our department were confirmed to have facial neuralgia after eliminating other local etiology for the accompanying pain. However only twenty-six out of seventy-four cases of Facial Neuralgia were diagnosed as Glossopharyngeal Neuralgia with a positive response to our diagnostic nerve block a described [2].

The youngest patient was 28 years of age and the oldest was 73 with a mean age of 49.27 years. Nineteen females and seven males. Pain was experienced on the left side in fourteen patients and on the right side in twelve patients. Twenty-one patients showed classical pattern of neuralgia, whereas five fell into symptomatic nature. Eleven were of the oro pharyngeal type, two of otitic type whereas the remaining thirteen showed a combination of both types (Table 1 and Figs. 1, 2, 3, 4). Twenty-three patients responded well to medical management with single or multi drug regimen. One patient was intolerant towards medication and neurolysis was performed with 99.9% absolute alcohol using intraoral anterior tonsillar pillar technique after which pain was completely relieved. Two patients responded poorly to medication and after alcohol neurolysis they showed good pain control supplemented with medication.

Table 1.

Patients data

Sr No	Age	Sex	Side	Otitic (O)/oropharyngeal (OP)	Classical (C)/symptomatic (S)
1	28	F	Left	Both	C
2	40	M	Left	Both	C
3	69	M	Left	Both	C
4	40	F	Left	Both	C
5	37	F	Left	OP	S
6	50	F	Left	OP	C
7	60	F	Right	Both	C
8	30	F	Left	OP	C
9	40	M	Left	Both	S
10	51	M	Left	OP	C
11	42	F	Right	O	C
12	62	M	Right	Both	C
13	45	F	Right	OP	C
14	56	F	Right	OP	C
15	63	M	Right	OP	C
16	45	F	Right	O	C
17	73	M	Right	Both	S
18	67	F	Left	OP	C
19	40	F	Right	Both	C
20	60	F	Left	Both	C
21	32	F	Left	Both	S
22	36	F	Left	OP	C
23	45	F	Right	Both	S
24	52	F	Left	Both	C
25	48	F	Right	OP	C
26	70	F	Left	OP	C

Fig. 1.

Sex distribution

Fig. 2.

Side distribution

Fig. 3.

Types of glossopharyngeal neuralgia

Fig. 4.

Age distribution

In our observation we found a prevalence of 0.2% for glossopharyngeal neuralgia in our patients with facial pain, however amongst the neuropathic pain the GPN was more prevalent with about 35% of all the cases. Amongst the cases diagnosed with GPN we had 73.1% female predilection as compared to only 26.9% male. 53.8% of cases had left sided and 46.2% on the right sided making it non-significant in sidewise predilection.

Discussion

History

The course of the glossopharyngeal nerve was described by Galen and it was identified as a separate entity by Fallopius. Weisenberg described this neuralgic pain in a cerebellopontine angle tumor for the first time in 1910. In this case the tumor impinged on both the sensory root of the trigeminal nerve as well as the glossopharyngeal nerve. Frazier sectioned the former, but pain from the 9th nerve persisted, and the case was considered a failure. The autopsy of this patient six years later revealed compression of the 9th nerve proving the existence of neuralgia pain associated with this nerve. In 1920, Sicard and Robineau described the true GN but were unsure of the nerve being the only source of pain and managed their patient with sectioning of the glossopharyngeal nerve as well as the cervical, sympathetic and pharyngeal branches of the vagus. A year later, Harris reported two cases and coined the term Glossopharyngeal neuralgia. The first extracranial section of the nerve was performed by Peet in 1919 and the first intracranial section in true GN was done in 1927 by Dandy [1].

Glossopharyngeal nerve, the ninth cranial nerve originates in the medulla and exits the skull through the jugular foramen thereafter forming the superior or jugular and inferior or petrous ganglia. It then goes on to give branches to the tympanic plexus, nerve to stylopharyngeus, pharyngeal branch, tonsillar branch, lingual branch and finally a branch to the carotid body. The in-depth function of the nerve was first described by Dandy after intracranial section of the nerve. He described that the nerve does not have a demonstrable motor function. Though the stylopharyngeus muscle is supplied by it, loss of its function cannot be demonstrated. The glossopharyngeal nerve provides sensory supply to the posterior third of the tongue, the anterior, lateral, and posterior walls of the pharynx from the lower nasopharynx to the epiglottis, including its posterior aspect, the tonsillar pillars, Eustachian orifice, and a narrow rim along the front of the soft palate including the uvula [1].

The International Association for the Study of Pain (IASP) defines GN as sudden, severe, brief, recurrent pain in the anatomical distribution of the glossopharyngeal nerve. Prevalence rate of GN in a year is about 0.7 persons/100,000 people [3–6]. In our institution we recorded a prevalence of 26 cases of GN out of 11,015 patients reporting to Department of over 31 months. GN has been described to have a prevalence of 2–3% that of Trigeminal neuralgia (TN), however, we recorded a prevalence of 26 cases of GN against 48 cases of TN amounting to 35% [7]. Literature cites an age range of 40–60 years, in our sample the youngest patient was 28 years old and the oldest 73 with a mean of about 49 years which is in accordance with the existing literature [5, 8, 9]. Left to right side ratio described in literature is 3:2, whereas in our sample we recorded 7:6 though no significant it has a slight predilection towards left side [8]. The gender ratio has been described to be 66.8:33.2 female to male and in our sample it is 19:7 with very high prevalence in female population [9].

Various classifications have been described in literature. Based on anatomical site it may be classified into otitic and oropharyngeal types [10]. In our sample eleven fell into the former category, two into the latter and the remaining presented as a combination. The international headache society classified GN into classical wherein the pain presented in episodes and symptomatic wherein the pain or discomfort was present continuously [11]. In our series only five patients suffered symptomatic pain.

A cause-based classification too has been described as idiopathic pain and secondary pain [12]. All cases diagnosed in our department had idiopathic pain. Idiopathic cranial nerve neuralgias are caused by vascular compression of the cranial nerve commonly at the root entry zone [13]. Compression by the posterior inferior cerebellar artery and vertebral artery are frequently seen to result in GN [13]. Pope was the first to report the association between GN and vascular compression in 1889. Magnetic resonance angiography (MRA) with time of flight images focused on the glossopharyngeal nerve and its ganglia were advised to our patients. However only 3 of 26 cases got MRA done due to financial constraint. In the MRA, there appeared to be compression by the vertebral artery in two cases of which one showed associated ectasia of the mentioned artery. In a single case there was compression from the posterior inferior cerebellar artery. Secondary GN has been reported in association with head and neck malignancies and cerebellopontine angle tumors. There has been a report GN from irritation of the superficial branches of the glossopharyngeal nerve from use of hard headphones which subsided once the etiology was removed [14].

The description of pain in GN amongst our patient sample ranged from needles pricking in the ear, inability to clean the tongue, cutthroat sensation and feeling of wound over the tongue. A patient localized pain near the uvula, palpated over the hard palate and claimed to have a swelling in the region though there was none. Fear of cancer was a common presentation of six patients in our series probably to blame for the multiple consults and no relief from treatment due to misdiagnosis. A patient walked into a cancer center requesting a tongue biopsy from the lateral border of the posterior portion of the tongue, which was reported as normal tissue on histopathology. The presentation of this condition has been described to be associated with cardiac syncope, neck metastasis and combined hyperactive dysfunction syndrome of the cranial nerves [15–17]. A single patient in our series reported syncope associated with the episodes of intense pain.

Diagnosis of GN may be confirmed using a diagnostic nerve block. This may be carried out by an application of 5% cocaine to the pharyngeal wall or by injecting a local anesthetic agent like lignocaine [18].

All patients were initially put on Carbamazepine 100–200 mg 8 hourly, and an antianxiety drug Cap Duloxetine 30 mg twice a day. In cases of refractory GPN a second antiepileptic drug such as Tab Pregabalin 75–150 mg or Tab Gabapentin 300 mg along with an increase in the dosage of Carbamazepine to 300–400 mg eight hourly was advised. Supplementation of Methyl cobalamin and Thiamine were routinely done in all the patients. Baseline renal and liver function tests were carried out and monitored on a three-monthly basis. One patient was not tolerant towards medication and chose to undergo alcohol neurolysis via and intraoral anterior tonsillar pillar technique using 0.9 mg 99.9% absolute alcohol, after which he was completely relieved of the pain. Two patients did not get relieved with even multi drug therapy and pain control was achieved with alcohol neurolysis and medication. Other methods of conservative management of neuralgic pain includes glycerol injection, injection of botulinum toxin A at the trigger point.

Surgical neurolysis by intracranial and extracranial section of the nerve has been described in literature. Neurosurgical management of the same with microvascular decompression by interposing a Teflon mesh in between the compressing vessel and the nerve is routinely performed in many centers with time tested results [13]. Balloon test occlusion as a diagnostic aid prior to microvascular decompression has been described [19]. Alternatively, the use of gamma knife radiosurgery using ≥ 75 Gy directed to the glossopharyngeal meatus has shown an 87% success rate [20].

Conclusion

Pain is an unpleasant sensation that causes discomfort. A toothache from a carious tooth, an earache from a perforation, a tongue pain from an ulcer, a pain on swallowing from tonsillitis can all be treated easily by treating the identifiable cause. However, a small segment of patients incessantly visits the otolaryngologist, the dentist, the physician, the maxillofacial surgeon only to be referred to the other, finally to the psychiatrist if neurogenic pain goes undiagnosed. Awareness of the clinical presentation of Glossopharyngeal Neuralgia is an important tool in the hands of the clinician. Clinical acumen to rule out organic causes of pain associated with a high level of suspicion could help in proper diagnosis and management of this relatively uncommon facial pain segment.

Abbreviations

GN

Glossopharyngeal neuralgia

TN

Trigeminal neuralgia

MRA

Magnetic resonance angiography

Compliance with Ethical Standards

Conflict of interest

I hereby declare that I have no Conflict of interest with any person either professional or personal.

Ethics Statement

I hereby state that I have obtained a written informed consent from my patients included in this study.